-- Online storage start-up Box.net kicked off its first developer conference Wednesday with announcements of new funding to fuel its rapid growth.

Box, a 6-year-old Palo Alto startup that helps workers share files and collaborate online, is in the midst of raising more than $50 million, the company said, bringing its total to $128 million. New investors include Salesforce.com, which helped to pioneer the adoption of cloud-based services like Box.

The one-day conference at San Francisco's Hotel Nikko highlighted the quick ascent of cloud-based companies that have effectively challenged more established rivals by competing on cost and ease of use. Like Salesforce before it, Box is seeking to upend competitors like SAP and Microsoft, which install systems physically at corporate sites rather than deliver them over the Internet.

"Software as a service," as it is known, is now an $89.4 billion industry, according to Gartner Inc.

"Everything we were talking about in the 1990s is actually working now," said Marc Andreessen, who co-created the first widely used Web browser and later co-founded Netscape.

Andreessen, who has invested in Box, said plummeting technology costs and the rise of mobile computing have led to new opportunities for companies that deliver services over the Internet. Companies like Box would not have been possible until recently, he said, because the cost of providing those services would have been too high for most companies to afford.

Box says it now has 7 million users and is used in 100,000 businesses, including 77 percent of the Fortune 500. More than 1,000 companies begin paying for the service each month.

"Our business is really to build a smarter enterprise," said Aaron Levie, the company's co-founder and CEO. "This is an enterprise that is more connected, more collaborative, able to get to their information more easily, able to generate more intelligence on top of their data and information. We're trying to build that kind of technology at Box."

The company's biggest announcement for customers was a designed synchronization service that coordinates files among multiple devices and users, making collaboration easier. Box Sync, as it is known, will be available on Apple computers for the first time.

The company also announced it will integrate with the Salesforce product Chatter, a social network that brings Facebook-like features to businesses. And it announced two other integrations: It will come pre-loaded on all HP computers and on Motorola Xoom tablets.